Method and apparatus for recording and reproducing sound



L. G. ,LARSEN Dec. 19, 1933.

METHOD AND APPARATUS FOR RECORDING AND REPRODUCING SOUND Filed July 10, 1929 2 Sheets-Sheet l INVENTOR Loan 6 '11617112912 M TTORNEY L. G. LARSEN Dec. 19, 1933.

TIETHOD AND APPARATUS FOR RECORDING AND REPRODUCING SOUND Filed July 10. 1929 2 Sheets-Sheet 2 INVENTOR ZozzzJ' 6- Zamen BY I 1 ATTORNEY Patented Dec. 19, 1933 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR RECORDING AND REPRODUCING SOUND Louis G. Larsen, Jersey City, N. J., assignor of one-half to George Ramsey, and one-fourth to David Stern, both of New York, N. Y.

Application July 10, 1929. Serial No. 377,148

16 Claims.

prior art, it was impossible to obviate faults in the original record, which faults were magnified during the reproducing operation.

It is recognized that a properly constructed auditorium enhances the beauty of a musical tone by what is sometimes referred to as room.

resonance. This quality of sound is produced through reflections from the room walls so that the auditor hears the same tone at slightly different times and at different intensities, and insuch manner as to make a blend of adjacent portions of the air sound wave. In the ordinary methods of recording tone, circumstances usually do not admit of surroundings which will produce the highest and most desirable room resonance qualities. records are being made simultaneously with moving pictures of public events where no studio refinements are available.

It has also been observed that by the present inventions not only undesirable characteristics of a record may be suppressed, but that desirable under-tones may be introduced into the final wave, which tones were not present in the original record, therefore, the present invention comprises methods' and apparatus for improving the quality of tones recorded and for obtaining desirable results from records made under unfavorable conditions.

Onefeature of the'present invention comprises blending adjacent portions of a sound record to produce a blended wave having added resonance qualities, and then utilizing the blended wave to make a record of the blended wave, or to reproduce the sound from the blended wave directly through a sound reproducer.

Another object of the present invention is the transmission of waves produced by a sound record through controllable filters and amplifiers whereby predetermined zones of audible frequencies may be suppressed or built up at the will of the operator; and the final wave from the filters may be utilized to operate a sound reproducer or to make a record of the filtered wave.

A further object of the present invention is the This is particularly true where sound (Cl. 17 9- -100A) production of waves, through separate means, from closely adjacent portions of the same tone record and blending the waves so as to introduce beat note waves of an undertone of the original recorded wave, and then either recording the blended wave or translating the same into a. sound wave. 7

A still further object of the present invention is a combination of the foregoing objects specifled, namely, the blending of adjacent portions of a wave produced from a recorded sound wave and then passing the blended wave through a plurality of audible frequency filters and amplifiers under the control of an operator so that any band of audible frequencies may be sub- 7 pressed or built up at the will of the operator and then utilizing the final wave from the filters to make a record of the blended filtered wave, or to pass this blended filtered wave directly to a sound reproducer to translate said wave into 7 said waves.

The above methods may be carried out by the use of aplurality of'pick-ups or reproducers operatedfrom adjacent portions of a single record; or from a plurality of identical records operated in synchronism, each of said records be-v ing provided with a'separate pick-up operating on adjacent portions of identical grooves .of said identical records. The waves from the'plurality of pick-ups, may be transmitted to a tone analyzer Where suitable wave filters and amplifiers are provided, each capable of adjustment at the will of the operator. The operator adjusts the filter and amplifier controls to bring out or suppress any particular audible frequency in 90,

accordance with'the judgment of the operator as to the requirements. for the final tone. The waves from the amplifiers and filters are blended into a final wave, which when desired may be further amplified. This final wave may be transmitted directly to a tone reproducing instrument where the final wave is translated into sound; or the final wave may be transmitted to a suitable recording apparatus where a new record is made of the final blended wave.

The preferred procedure in carrying out the present invention is to utilize well known electrical pick-ups, amplifying, filtering apparatus, and an electrically operated loud speaker. The final electric wave preferably is run, directly to the loudspeaker, and the operator adjusts the control until the desired quality of tone is obtained. The records are then replayed with the electric wave being run directly to an electrically controlled recording instrument where'an improved record is made of the blended tone. This improved record is then used as a source by which the improved blended wave is translated into sound, through suitable well known apparatus. Another convenient method is to operate the loud speaker and recording instru ment simultaneouslyso that the operator hears the tone as it is being recorded, and thereby controls the recorded tone as desired. There may also be situations where it is not necessary or desirable to make a record of the blended tone and under these conditions, the blended tone is run to a loud speaker where it is directly translated into sound waves. a

The disclosure herewith is diagrammatic of the preferred form of the invention. It is to be understood, however, that the invention may be practiced in other forms as will be'readily appreciated by those skilled in the art and therefore, the present disclosure is understood as being illustrative and not to be considered in the limiting sense.

Referring now to the drawings, Fig. 1 is a diagrammatic view of the preferred embodiment of the invention utilizing a plurality of identical records Fig.2 is a diagrammatic view illustrating the invention as practiced from a single record.

Referring now to the drawings and more especially to Fig. 1, a plurality of turn tables 1, 2, 3, and 4 are mounted upon a suitable frame and are all synchronized in such manner as to be driven at the same rotative speed. As an illustrative embodiment of such construction, an electric motor 5 drives a suitable governor mechanism 6 which is connected by a belt 7 with turn table 1 in order to drive this turntable at a predetermined rotative speed dependent upon the speed of the electric motor 5 as controlled by the speed governor 6. The shaft of the turn' table 1 is connected by a continuous chain 8 with gears 9, 10, 11 and 12 respectively connected with the shafts of turn tables 1, 2, 3, and 4, so that the rotative speed of all of the turntables is exactly the same. Idler gears 13 are adapted to hold the drive chain taut and in'contact with the gears9, 10, '11 and 12. The turn tables carry phonograph records 14, 15, 16 and 17, which records preferably are all made from identically the same record die, so that the records are identically the same on each of the turn tables.

The tone grooves of each of these records start at a point S indicated thereon. Electric pick-ups 18, 19, 20 and 21 are provided for each turn table. The needle point N18 of electric pick-up 18 is set on the starting line S. The needle point N19 of the electric pick-up 19' is advanced slightly from the starting point S. The needle point N-20 of the pick-up 20 is advanced still further from the starting point S and the needle point N21 of the pick-up 21 is furthest advanced from the starting point. This setting is accomplished when all of the'turn tables are stationary and is brought about by the proper positioning of the records on the turn tables relative to the respective needle points. Preferably, the records are securely held against slippageon the turn tables by means of clamp screw heads 22 which are screw threaded on to spindles carried by the turn tables.

In the preferred embodiment as illustrated in Fig. 1, a'blending and control unit 24 is connected with each electric pick-up. For example, the

circuit 25 leading from pick up 18 has an independent connection to the control 24. Y The circuit 26 from the pick-up 19 is likewise independently connected to the control unit 24 and the circuits 2'? and 28 from pick-ups 20 and 21 are similarly independently connected to the control unit. As illustrated in this form of the invention suitable amplifying tubes 29, 3G, 31 and 32 of the ordinary three electrode type in common use in radio are respectively connected in the circuits 25, 26, 2'7 and 28. Suitable control buttons 34, 35, 36, and 3'7, which may operate variable resistances, are likewise arranged to control the circuits from the electric pick-ups'through the amplifying tubes. These circuits preferably include wave bandfilters, that a series of graded wave band filters, one in each of the pickup circuits, so that the entire audible wave band is covered by the combined total action of all the filters when all circuits are full open. For eX- ample, the circuit from pick-up 18 includes a filter taking the lowest base notes to the medium base notes. The filter in the circuit from electric pick-up 19 takes the next adjoining band of audible frequency, the filter in the circuit from the pick-up 20 the next higher band, and the circuit from the pick-up 21 takes the highest band of audible frequency, so that the entire range of audibility is covered by the four filter channels. It is to be understood that each filter is constructed in such manner as to transmit a particular wave band, and to filter out other wave bands. The control knobs 34, 35, 36 and 37 control the effectiveness of any particular filter so that the filter may be effective in the circuit either 100% thereby completelytransmitting a particular wave band or the same filter may be rendered substantially ineffective, thereby cutting out'the entire audible wave band through that particular unit. In the embodiment illustrated the circuits from all of the pick-up members after them have passed through amplifiers, filters, and controls therefor are transmitted into an amplifier whi h may comprise a suitable amplifying tube 38 with a control knob 39 therefor and from this last stage to the output circuit 40. The output circuit may run through a suitable switch 4lto a suitable sound reproducer 42. The switch 41 permits the circuit to be changed from the sound reproducer into a circuit 44 which leads to a recording instrument 45. The type of recording instrument illustrated is that of a wax record type, carrying a was blank on a suitably rotated turn table, and wherein the cutting tool is electrically operated in such manner as to engrave a tone groove on the wax surface and thereby produce a record from the electrical impulses on the output circuits 40 and 44.

Certain phases of the present invention may be carried out with a sin le record and a plurality of reproducers operating on the single record. Other phases of the invention could be carried out by a single reproducer operating on a single record and with the electrical current originating from a single pick-up distributed through asuitable bank of filters, each of which will transmit predetermined frequencies and will block other frequencies. In this way, the tones from a single reproducer may be analyzed and certain frequency bands suppressed while other frequency bands are amplified and then the resulting wave treated in accordance with the present invention and either used to make a new record or to reproduce the sound directly.

W ave band filters are Well known in the electrical artsan'ol therefore any well known'filter system may be used for the purposes herein specified, and one example of such filters is illustrated in the United States patent to Hahnemann 1,674,683, patented June 26, 1928.

Referring now more specifically to Fig. 2, a suitable turntable 46 carries a record 4'7, and the electrical pick-ups 18, 19, 20 and 21 are arranged with their needle points N-l8, N-19, N20, and N-2 1 onclosely adjacent portions of the same tone groove of the record. The circuits 25, 26, 2'7 and 28 from these reproducers are all con-- nected with suitable filter-ing and amplifying apparatus in accordance with the disclosure diagrammatically illustrated in Fig. 1. In other Words, Fig. 2 is a substitution of a single record and a plurality of electrical pick-ups for the four records and four independent pick-ups illustrated in Fig. l.

It will be apparent to those skilled in the art that variations and departures may be made fromthe present disclosure without departing from the scope of the invention, for example, the'wave from a single reproducer, or from aplurality of reproducers may be run through audible fre quency filters so that the entire group of filters areoperative upon the circuit from a single pickup or'a; plurality of pick-ups, and the filtered waves blended together, amplified and translated into sound waves. Furthermore, it is within the scope of the present invention to provide tuned circuitsfrom each pick-up whereby the entire circuits from a particular pick-up including the wiring of the pick-up head itself, is tuned to a particular audible frequency band, with suitable controls in the circuits, so that by the utilization of a plurality of identical records and pickups, each of which are specifically tuned to a definite audible wave band, the blending inthe final output wave is brought about by control of each tuned circuit. It also may be desirable in some cases that the pick-ups shall operate upon identically the same portions of a tone record, thereby omitting the resonance characteristic, but on the other hand, producing output waves which may be blended as to tone bands in accordance with the desire of the operator.

Where the needle points of the pick-ups are arranged on substantiallly the same portions of the several tone grooves,'it is possible to cause the blended waves from the several pick-ups to produce beat notes of an undertone or fundamental of the original recorded tone. In this way, the resulting tone wave is built up and enriched by desirable characteristics which are not present in the original record. 7

While the ordinary phonograph record and electric pick-up have been illustrated as the preferred embodiment of the invention, it is to be understood that the present invention is.

applicable to films or any other form of sound recording and reproduction.

The term single wave. used herein inthe specification and claims means a single complex wave of audible frequency. It does not mean a wave of uniform amplitude or of uniform'frequency, but simply a wave which may be translated into a single linear record. The term translating into sound means any apparatus such as a loud speaker or a record associated with sound producing reproducers; in other words, it refers to anything which may be utilized to translate the wave into sound. The term electric pick-upf herein used is intended to cover any form of magnetic, microphonic, variable resistance, photoelectric cell, or any other apparatus whereby a sound record may be utilized to translate a sound record into a corresponding electric wave or waves. .Having described my invention I claim:

'1..The method of sound reproduction comprising producing waves of audible frequencyfrom adjacent portions of a single linear sound record, blending saidwaves, and translating the blended waves into sound waves.

2. The method of sound reproduction comprising producing waves of .audible frequency from closely adjoined portions of a single linear sound record, blending said audible waves into a single wave, and translating said single wave into audible sound.

3. The method of sound reproduction comprising producing a plurality of independent waves of audible frequency from a. sound record, and modulating said waves by diminishing the amplitude of a predetermined band of audible frequency and increasing the amplitude of other bands of audible frequency and blending the modulated frequency waves from different portions of a single linear sound record, analyzing the said waves into frequency bands, controlling the amplitude of said waves in said analyzed bands, and blending the independent controlled waves into a single Wave of audible frequency.

5. The method of reproducing sound comprising producing waves of audible frequency through a plurality of independent channels from adjacent portions of a linear sound record, controlling the amplitude of the waves in each of said channels and blending the controlled waves into a single wave of audible frequency.

6. The method of reproducing sound comprising producing waves of audible frequency from a plurality of identical sound records through independent channels, controlling the audible frequency waves in each of said channels as to the amplitude of said waves, passing through said channels, and blending the controlled waves into a single wave of audible frequency.

'7. The method of sound reproduction comprising producing audible waves from said original record through a plurality of channels, controlling the amplitude of the waves in each channel, blending the controlled waves into a single wave of audible frequency, and controlling a sound recorder by said blended wave.

8. The method of reproducing sounds from a record having different characteristics from an original sound record, comprising producing a plurality of independent audible frequency waves from said original sound record, which waves have the same characteristic as said original sound record, causing said waves to travel through a plurality of controlled channels, modulating the waves in at least one of said channels, blending the modulated waves from said channels into a single wave of audible frequency, and controlling a recording apparatus by said blended wave.

9. The method of producing a sound record having characteristics differing from an original sound record comprising producing a plurality of independent waves of audible frequency from an original record, passing said sound waves through a plurality of independent channels, modulating the waves in said channels,

blending the modulated waves into a single blended Wave, and recording the blended wave.

10. The method of introducing undertones in sound reproduced from a sound record in whichv said undertones are not present, comprising simultaneously producing a pluralityof independent waves of audible frequencies. from' such adjacent portions of the same tone recording as to cause beat waves of the undertone desired, blending the said waves into a single wave having said undertones, and translating said single wave into sound. V

11. The method or" introducing undertones in sound reproduced from a sound record'in which said undertones are not present, comprising simultaneously producing a plurality of independent waves of audible frequencies from such adjacent portions of'the same tone recording as to cause beat waves of the undertone desired, blending the said waves into a single wave having said undertones, and making a new record of said single wave.

e 12. An apparatus of the character described comprising a plurality of turn tables adapted to carry phonograph records, a pick-up for each turn table, means to drive said tables synchronously, filters connected with said pick-ups, control means for controlling the eifectiveness of saidfilters, a common circuit for the output from all of said filters, amplifying means in said common circuit, and recording means operatively connected with the amplifying means.

13. A device of the class described. comprising a plurality of. turn. tables for phonograph records, an electric pick-up for each turn table,- means to drive said turn tables synchronously, means to blend the circuits from .all of said. pick-ups into a single circuit, amplifying means in said single circuit, and recording means operatively connected with said amplifying means.

14. A device of the class described comprising a plurality of turn tables for phonograph records, an electric reproducing pick-up for each turntable, amplifying means in each pick-up circuit, means to control the current flowing through each pick-up circuit, acommon circuit from all of said pick-up circuits, and recording means in said common circuit.

15. In a device of the class described, a plurality of electric pick-ups arranged in series relative to a common tone groove, control means for each pick-up circuit, amplifying means, a common output circuit for all of said pick-up circuits, and recording means in said common output circuit.

16. In a device of the class described, a sound record, a plurality of electric pick-ups operative on said sound record, means to blend the currents from said pick-ups, and means to translate said blended current into a sound record.

LOUIS G. LARSEN. 

